I'd say 2 things.First, read this paper Enhanced Dollar Cost Averaginghttp://papers.ssrn.com/sol3/papers.cfm?abstract_id=2008465The first section neatly discusses the problems with DCA, but summarises "Thus, dollar-cost-averaging may be inferior to the optimal strategy, but is superior to the strategy most investors are likely to adopt as a result of their human nature."

With a several $M lump sum, I'd say that you have no worries either way. Even suboptimally getting in, you'll still have a potload of money.

Heck, with a 2M+ lump sum, I'd be inclined to put 500K into bonds & preferred stocks for the income, and invest the rest.

2nd,FWIW...when I retired I moved 500K of my 401k to be managed by Fisher Investments. They invest mainly in stocks, with very little going into ETFs. They had it all invested in only a couple of weeks. No DCA'ing at all.

Announcements

Foolanthropy 2014!
By working with young, first-time moms, Nurse-Family Partnership is able to truly change lives – for generations to come.

When Life Gives You Lemons
We all have had hardships and made poor decisions. The important thing is how we respond and grow. Read the story of a Fool who started from nothing, and looks to gain everything.

Work for Fools?
Winner of the Washingtonian great places to work, and Glassdoor #1 Company to Work For 2015! Have access to all of TMF's online and email products for FREE, and be paid for your contributions to TMF! Click the link and start your Fool career.